modems firewall

[fivealive]

so i was having internet issues yesterday and well trying to figure out what was going on i went into the modem and i noticed it has a firewall and its disabled.

well my question is should i turn it on and what exactly does it do or doesnt do?

(on a side note the internet issues turned out to be on my isp end apparently someone cut a cable and knocked out phone tv and internet for the whole block)

iv attached a picture of my modems page

[David H. Lipman]

Modems don't have firewalls. Since the SMCD3GN supports DOCSIS 3.0 then it is a Cable Modem+Router. That means a Router has been combined with a DOCSIS (Cable) Modem. The modem part only decodes the modulated network pipe from the carrier signal that uses Quadrature Amplitude Modulation (QAM).

It is the Router part of the modem that includes a firewall. Not all modems have the additional Router.

You will have to define "having internet issues" because enabling a Firewall does not cure Internet issues. Firewalls are about isolating the WAN (Internet) from the LAN and provide protection and a barrier from exterior influences.

[fivealive]

The internet issues where the internet kepy turning off. It turns out that construction cut some fiber optic cables and caused the internet and the home phone and cable tv to go out for a couple hours

[David H. Lipman]

The fact that you lost the triple-play was the clue that it was not an issue within your home and the Firewall wasn't part of the equation.

Glad you got it sorted out.

[fivealive]

Yes I know that it wasn't part of the problem the firewall was never on to begin with. My question was should I turn it on and if so what kind of effect would it have on the internet useage if any at all. Sorry I didn't make myt question very clear

[David H. Lipman]

Sure, enable it. The question is will enabling it provide sub-menus such that you have greater control such is protocol rules or is it merely an On/Off switch.

[fivealive]

i did provide a picture of what i see when i go to the firewall section and before turning it on their is 2 options. one labeled: enable firewall module and a second labeled : Enable SIP Application Layer Gateway Service

should i turn both on

[David H. Lipman]

Yes, I saw the graphic but doen't know if there are sub-menus pertinent to the Firewall.

I don't know what Enable SIP Application Layer Gateway Service is so offhand I'd say no.

This thread might be helpful.

http://www.dslreport...n-Layer-Gateway

And this...

http://en.wikipedia.org/wiki/Application-level_gateway

[fivealive]

well i enabled it and here is the list of sub menus (see picture)

[David H. Lipman]

Access Control - Could mean to block access to Internet services from within the LAN.

Special Application - Could be port forwarding/port triggering

URL Blocking - Rules to block sites

Schedule Rule - Rules to be enacted at a give time or for a given time frame.

Email/Syslog alert - Generate email messages to a specified address based upon given events

DMZ - De-Militarized Zone - IP address that is open to Internet as if there was no Firewall. It is like when a PC is directly connected to the Internet.

[fivealive]

yeah seems your correct on what each of those does pretty much

i dont need url blocking at this time nor do i need the schedule rule or the DMZ but the email alert sounds like it could be useful i think i might call my isp and ask about setting that up or if i even can and well im at it ill ask about the other option on the firewall the Enable SIP Application Layer Gateway Service is

once done ill post back here what they said

[fivealive]

so apparently my isp doesnt deal with the built in firewall at all and they dont even know what the option is.

[David H. Lipman]

Knowledge of what Enable SIP Application Layer Gateway Service is not something you'll get from 1st level ISP support. It is an advanced feature. The two URLs can provide information but I don't see it being needed to be enabled.

[fivealive]

alright thanks

ill just ignore it then.